KR102063097B1 - Electrical leak detecting apparatus and electrical leak detecting method for improving the electrical leak detecting accuracy - Google Patents

Abstract

An electrical leak detecting apparatus is disclosed according to an exemplary embodiment of the present disclosure. The earth leakage detecting apparatus may include a ground voltage measuring unit measuring ground voltage, an ADC unit sampling the measured ground voltage and converting the measured ground voltage into a digital value, and an effective value calculating unit calculating an effective value of the ground voltage converted into the digital value. A Fourier transform unit for performing a Fourier transform on the measured ground voltage based on the effective value of the ground voltage and calculating a voltage for each harmonic component that is an integer multiple of a fundamental frequency—the power frequency of an AC commercial power source; and based on the voltage for each harmonic component. A content calculation unit for calculating a voltage content ratio of the fundamental frequency to a voltage obtained by adding the voltages for each harmonic component, and a total harmonic distortion factor and a distortion factor for each harmonic component based on the voltage for each harmonic component; A harmonic distortion rate calculating unit for calculating a value, and converting the digital value into the digital value for a predetermined time T1. A zero crossing calculation unit for calculating the number of zero crossings through which a ground voltage passes a zero voltage and an effective value of the ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, and the zero On the basis of at least one of the number of crossings, the ground voltage is determined to be caused by the leakage of the AC commercial power supply, and based on the determined result, the ground fault to determine the area in which the ground voltage is measured as a suspected short circuit region Suspect zone determination may be included.

Description

ELECTRICAL LEAK DETECTING APPARATUS AND ELECTRICAL LEAK DETECTING METHOD FOR IMPROVING THE ELECTRICAL LEAK DETECTING ACCURACY}

TECHNICAL FIELD The present invention relates to the field of power, and more particularly, to an apparatus and a method for improving the accuracy of earth leakage detection.

In the event of a ground fault (leakage) of a power line buried in the ground, a device and method for determining whether a short circuit occurs in a multiple common ground environment and detecting a short circuit location have been disclosed.

Republic of Korea Patent No. 10-1559533 "Removable Earth Leakage Detection Apparatus and Method",

Republic of Korea Patent Application Publication No. 10-2017-0007696 "Earth leakage sensing device and method in a neutral ground multi-ground environment",

In addition, the non-patent literature discloses a low voltage line path and an earth leakage detection technology in the neutral ground common ground environment of the new power technology No. 104.

In order to detect the ground fault (electrical leakage) which accounts for the majority of the power equipment failure, the electric shock dangerous voltage charged to the power equipment flowing out from the insulation failure point to the ground, the neutral ground of the power supply (transformer) is grounded to the ground, When a short circuit occurs, the fault (leakage) current is constantly monitored by the magnitude of the current returned to the grounded neutral point of the power supply to detect a short circuit occurrence and eliminate the cause of the fault. In other words, the unbalanced load current feedback among the currents returned to the power supply (transformer) causes the neutral wire to return to the neutral point of the power supply (transformer) through the earth.

However, if the ground fault occurs remotely from the power supply (transformer), the earth resistance may increase and the fault current may not be returned to the grounded neutral point of the power supply. As a result, it was impossible to detect a short circuit, so that power was continuously supplied without any protective measures, thereby increasing the risk of electric shock.

In order to prevent the risk of electric shock due to earth resistance depending on the power supply and the location of the earth leakage, the multiple common grounding method of earth grounding the neutral wire in the middle of the power line according to the provisions of IEC 60364 etc. was introduced. Grounding only one point of (transformer) to the ground by grounding several points of the power line (neutral line) where the grounded point of the power is extended to the ground, shortening the fault (leakage) current return distance and minimizing the effect of earth resistance To prevent.

However, when multiple neutrals of a power line are grounded in multiple places, an earth loop is formed in the ground section, so that normal (load unbalanced) feedback current is circulated to another neutral line instead of fault (leakage) current, or fault (leakage) current is neutral. Since the fault current and the normal return current cannot be distinguished when flowing into the neutral line through the multi-ground, a vector sum of the current flowing through the power line is obtained, which causes a problem of failing to detect a short circuit or a suspected short circuit section.

In order to solve this problem, in the prior art, as shown in FIG. 1, the earth leakage level and the earth leakage section are detected as shown in FIG. The technology for injecting a ground fault signal into a power line and detecting the ground fault point has been developed.

1 is a flow chart of the earth leakage detection by measuring the ground voltage used in the prior art. That is, measure the ground voltage (V1) between the neutral point (unmarked) and the remote ground of an arbitrary ground point or the adjacent customer equipment grounded with the ground point, and at this time, V1 exceeds the threshold value (103) and the power frequency component (Vf). ) And a change rate in which the voltage value of V1 is maintained even when the internal impedance is changed (104). 102) connects the earth leakage detection signal generator to the power line within the suspected leakage fault section (107) and moves along the buried path of the power line (108,109) and transmits the earth leakage detection signal transmitted by the earth leakage detection signal generator; The ground fault detecting apparatus 106 detects the ground (110, 111, 112) and determines the ground fault point position by using the ground fault detecting apparatus (110).

FIG. 2 illustrates a front end circuit and an internal algorithm configuration of a ground fault detecting apparatus for performing two separate tasks shown in FIG. 1, that is, a ground fault suspect section 102 and a ground fault inspection task 106. . Measure the voltage (V1) between the neutral line (unmarked) and the remote ground of the customer's equipment close to any ground point or the ground point (122), and the ratio between the included power frequency (50 or 60 Hz) voltage (Vf). To find the content of the earth leakage as shown in [Equation 1], change the input impedance of the measurement circuit as shown in [Equation 2] (123) to obtain the rate of change of the measured voltage magnitude (123) to investigate the leakage suspected interval (102).

If the ground voltage measured at any ground point is determined to be a ground fault section, a ground fault point detecting operation 106 for identifying the ground fault position is performed.

Figure 3 shows the configuration of the equipment for the earth leakage point exploration within the suspected earth leakage section. The earth leakage detection signal generators 132 and 133 are connected to the power lines 202 and 203 in the suspected earth leakage section, and the magnetic field signals 141 and 142 generated by the current signals transmitted by the current pulse signal device 132 are detected on the ground. The ground fault detecting apparatus 131 detects the voltage pulse signal 140 included in the ground voltage 212 at the ground at the signal generation time that the magnetic field signals 141 and 142 notify. The voltage pulse signal 140 is designed to generate the next voltage pulse signal at a predetermined interval from the time at which the magnetic field signals 141 and 142 are received, so that the earth leakage detecting device 131 has a next voltage pulse signal 140 at a time interval. The signal included in the ground voltage is detected at the time of occurrence, and the maximum point of the signal is determined as an earth leakage point (128).

As described above, a technology for detecting a leakage power supply position regardless of the neutral multiple grounding by detecting the leakage voltage pulse signal 140 included in the ground voltage on the ground within the suspected earth leakage section has been used in the field. An error of determining that the earth potential is shorted as shown in FIG. 5 even when the earth potential is increased by the stray voltage generated when the unbalanced load current flowing through the grounding point is caused by the induced voltage of the conductor of the magnetic field or the electrostatic coupling or the multi-ground neutral wire Is committing.

That is, in the previous technology, the content rate and the voltage fluctuation rate are used to distinguish between the actual leakage of dangerous voltage flowing into the ground due to the insulation failure of the power equipment transmitting or storing commercial power and the rise of the ground potential caused by the induced voltage or stray voltage parasitic around the power line. While trying to distinguish by measuring the difference in the application in the field, as shown in FIG.

In order to solve this problem, there is a need for a method and an apparatus for accurately distinguishing an organic or drifting power parasitic around a real power supply and a power line.

Disclosed is an electrical leak detecting apparatus according to an exemplary embodiment of the present disclosure for realizing the above problems. The earth leakage detecting apparatus may include a ground voltage measuring unit measuring ground voltage, an ADC unit sampling the measured ground voltage and converting the measured ground voltage into a digital value, and an effective value calculating unit calculating an effective value of the ground voltage converted into the digital value. A Fourier transform unit that calculates a voltage for each harmonic component that is an integer multiple of a fundamental frequency—the power frequency of an AC commercial power source, by Fourier transforming the measured ground voltage based on the effective value of the converted ground voltage, and the voltage per harmonic component. A content rate calculating unit for calculating a voltage content ratio with respect to a fundamental frequency to a voltage obtained by summing the voltages for each harmonic component, a total harmonic distortion and a harmonic distortion for each harmonic component based on the voltage for each harmonic component; Harmonic Distortion Calculation Unit for Computing Factor), and Converts to the Digital Value During Preset Time T1 A zero crossing calculation unit for calculating the number of zero crossings through which the ground voltage passed through the zero voltage and the effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, and the distortion rate for each harmonic component And based on at least one of the number of zero crossings, determine the ground voltage as being caused by a short circuit of the AC commercial power, and determine an area in which the ground voltage is measured based on the determined result as a ground fault suspect region. It may include a suspected short circuit area to determine.
Alternatively, the preset time T1 may be a time that is a preset integer multiple of the period of the AC commercial power.
Alternatively, a distortion calculation unit for calculating the number of distortions for changing the polarity of the change amount of the ground voltage based on the ground voltage converted into the digital value for each sample included in the preset time T1 from the ADC unit And the leakage suspected area determining unit is based on at least one of an effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, the number of zero crossings, and the number of distortions. The suspected short circuit area can be determined.
Alternatively, the distortion calculator may be configured to determine the polarity of the first change amount of the digital value of the first ground voltage sampled and converted and the digital value of the second ground voltage sampled and converted after the next sampling period. When the digital value and the polarity of the second change amount of the digital value of the third ground voltage converted by sampling after the next sampling period are different, it may be determined that the distortion occurs due to harmonics, and the number of distortion may be calculated.
Alternatively, the ground voltage measuring unit is in parallel with an electrode connected to a measuring point a which is an arbitrary point on the earth surface, an electrode connected to a measuring point b which is an arbitrary point on the earth surface different from the measuring point a, between the measuring point a and the measuring point b And a voltage measurer configured to measure a voltage between the resistor array and the resistor array connected to each other.
Alternatively, the zero crossing calculation unit may calculate the number of zero crossings that pass through the zero voltage when the polarity of the ground voltage changes during the preset time T1.
Alternatively, the earth leakage suspected zone determining unit may include an effective value of the converted ground voltage exceeding a preset threshold voltage value, the voltage content exceeding a preset voltage content, and the total harmonic distortion rate being a preset total harmonic distortion rate. The ground voltage is less than a predetermined distortion rate for each harmonic component, and when the number of zero crossings coincides with a preset number of times, the ground voltage may be determined to be generated by the leakage of the AC commercial power supply. have.
Alternatively, the earth leakage suspected zone determining unit may include an effective value of the converted ground voltage exceeding a preset threshold voltage value, the voltage content exceeding a preset voltage content, and the total harmonic distortion rate being a preset total harmonic distortion rate. The ground voltage is less than a predetermined distortion rate for each harmonic component, the number of zero crossings corresponds to a preset number of times, and the ground voltage is less than a preset number of times. This may be caused by a short circuit.
Alternatively, a magnetic field signal receiver including a magnetic field sensor to receive a magnetic field signal generated from an exploration current generator for earth leakage point sensing, and a pulse voltage component received after a predetermined time from the magnetic field signal to generate a ground fault detection voltage signal. A ground fault detection voltage signal receiver for determining a ground fault detection voltage signal generated from a device; a power line embedding path search unit for determining a path of a power line embedded in the ground fault suspect area based on a point where the magnitude of the magnetic field signal is the maximum point; The apparatus may further include a ground fault determining unit configured to determine a ground fault point of the embedded power line based on the magnitude of the ground fault detection voltage signal.
Alternatively, the ground fault determining unit may set a logic value according to whether the ground fault detection voltage signal is received, and coincide with the set logic value and a logic value of the ground fault detection voltage signal generated by the ground fault detection voltage signal generator. The point at which the magnitude of the ground fault detection voltage signal has a maximum value may be determined as the ground fault point.
Disclosed is a short circuit detecting method according to another exemplary embodiment of the present disclosure. The earth leakage detection method includes measuring a ground voltage, sampling the measured ground voltage and converting the measured ground voltage into a digital value, calculating an effective value of the ground voltage converted into the digital value, and the effective of the converted ground voltage. Calculating the voltage of each harmonic component based on a value by Fourier transforming the measured ground voltage based on a value, and calculating the voltage of each harmonic component based on the voltage of each harmonic component. Calculating a voltage content ratio for the fundamental frequency to the sum of the voltages, calculating a total harmonic distortion and a harmonic distortion factor based on the voltage for each harmonic component, a preset time Zero C (Zero C) through which the ground voltage converted to the digital value passes the zero voltage during (T1) calculating the number of rossing) and the ground voltage based on at least one of an effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, and the number of zero crossings. The method may include determining that the current has occurred due to a leakage of commercial power, and determining the area in which the ground voltage is measured as a suspected short circuit based on the determined result.

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According to an embodiment of the present disclosure, any ground voltages (leakage voltages) caused by parasitic voltages existing around commercial power equipment and insulation failures that may cause human life and equipment accidents may be provided regardless of the power line configuration. It is possible to prevent the electric shock by improving the accuracy of earth leakage detection by suggesting the means and method to identify and distinguish the potential rise position.

In addition, other features and advantages of the present disclosure may be newly grasped through embodiments described below in connection with the present disclosure.

1 is a flowchart of a work for earth leakage detection in the prior art.
2 is a diagram illustrating an internal configuration of the electrical leak detecting apparatus 131 in the previous technology.
3 is an installation configuration diagram of an earth leakage detection signal device and an earth leakage detection device for detecting an earth leakage point.
4 shows generation of induced voltage due to power line, power failure, and magnetic field coupling.
FIG. 5 illustrates that the previous technology misunderstands the rise of the ground potential as a true short circuit due to parasitic voltages (organic and drift voltages) around power lines.
6 is an illustration of a ground voltage waveform at a location where a true short circuit occurs.
7 is an example of a ground voltage waveform raised by a power line parasitic voltage.
8 is an example of the ground voltage waveform raised by the power line parasitic voltage.
9 is a waveform of a ground voltage raised by true leakage and a spectrum according to frequency (harmonics) during Fourier transform.
10 is a spectrum of earth voltage waveforms raised by parasitic voltages and frequencies (harmonics) during Fourier transform.
Fig. 11 shows the number of distortion count occurrences in the ground voltage waveform raised by the parasitic voltage.
12 illustrates a distortion counting method in a distorted waveform.
FIG. 13 is a flowchart illustrating a distortion count as shown in FIG. 12.
FIG. 14 shows a configuration of detecting an earth leakage suspect area of the earth leakage detecting device 131 where the ground voltage is increased due to a true earth leakage without a separate earth leakage detection signal transmission (injection).
FIG. 15 is a flow chart of a leak suspected area search business of FIG. 14.
FIG. 16 is a circuit diagram illustrating an electrical leak point detection configuration using a ground fault detection device after a ground fault detection signal is transmitted (injected) to a power line located in the suspected ground fault zone of FIG. 15.
FIG. 17 is a flow chart of an electrical leak point probing operation of FIG. 16.
Fig. 18 illustrates exploration of the earth potential rise due to a true short leak, that is, exploration of a short circuit suspected section.
FIG. 19 illustrates a short circuit point exploration in a short circuit suspected section.
20 is an example of a screen displaying a result of exploring a place where the ground voltage is increased due to a true short circuit without additional earth leakage detection signal transmission (injection).
FIG. 21 is an example of a screen displaying a result of Fourier transforming a ground voltage whose potential is increased due to the true leakage of FIG. 20.
FIG. 22 is an example of a screen showing a waveform of a ground voltage whose potential is increased by a true short circuit in FIG. 20.
FIG. 23 shows an example of a screen displaying a result of a short-circuit detection by transmitting (injecting) a short-circuit detection signal to a power line in a corresponding section after determining a place where the ground potential rises due to the true short-circuit of FIG. 20; have.
24 is an example of a screen displaying a result of exploring a place where the ground voltage is increased by the parasitic voltage without a separate earth leakage detection signal transmission (injection).
FIG. 25 is an example of a screen displaying a result of Fourier transforming a ground voltage whose potential is increased by the parasitic voltage of FIG. 24.
FIG. 26 is an example of a screen showing a waveform of a ground voltage whose potential is increased by the parasitic voltage of FIG. 24.
27 is a screen showing the result of the earth leakage detection signal being transmitted (injected) to the power line to check whether the earth potential is increased due to the parasitic voltage of FIG. An example is shown.
28 is an example of a ZCC / DC function selection screen for determining waveform distortion.
29 is a block diagram of an electrical leak detecting apparatus according to another exemplary embodiment.
30 is an illustration for explaining a method of measuring a ground voltage in another embodiment of the present invention.
31 is an illustration for explaining a method for calculating the number of distortions according to another embodiment of the present invention.
32 is a flowchart illustrating a method of calculating the number of distortions according to another embodiment of the present invention.
33 is a diagram illustrating a protocol for receiving a magnetic field signal and receiving a short circuit detection voltage signal according to another embodiment of the present invention.
34 illustrates an example of a relationship between a notification of start time of a ground fault detection voltage signal and a time at which the ground fault detection voltage signal is measured according to another embodiment of the present invention.
35 is a flowchart of a method of determining a suspected short circuit region according to another embodiment of the present invention.
36 is a flowchart illustrating a method of determining a ground fault point according to another exemplary embodiment of the present invention.

Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In this specification, various descriptions are presented to provide an understanding of the present disclosure. It is evident, however, that such embodiments may be practiced without these specific details. In other instances, well-known structures and devices are provided in block diagram form in order to facilitate describing the embodiments.

As used herein, the terms “component”, “module”, “system” and the like refer to computer-related entities, hardware, firmware, software, a combination of software and hardware, or the execution of software. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an thread of execution, a program, and / or a computer. For example, both an application running on a computing device and the computing device can be a component. One or more components can reside within a processor and / or thread of execution, and a component can be localized within one computer or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may for example be signals having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and / or data over a network such as another system and the internet via signals and / or signals from one component). May communicate via local and / or remote processes.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure should not be limited to the embodiments presented herein but should be construed in the broadest scope consistent with the principles and novel features presented herein.

As used herein, the terms “current pulse generator” and “exploration current generator” can often be used interchangeably. In addition, the terms "voltage pulse generator" and "leakage detection voltage signal generator" as used herein may often be used interchangeably.

The present invention is susceptible to short-circuit in order to limit the target to be explored for efficient short-circuit detection in a multi-near ground Neutral (MEN) environment with a plurality of "Power Line PEN" (Protective Earthed Neutral) grounding the neutral in the middle of the power line The present invention relates to a device and a method for providing Suspicious earth leaking area and leakage power information.

A parasitic voltage source that is always present near a power facility charged with commercial power, that is, an earth leakage voltage generated by the neutral return current flowing through the ground according to the induced voltage or neutral ground of the conductor combined with the power line and the electrostatic or magnetic field. As a result of measuring the waveform of such a case to distinguish it from, it was found that it has the form as shown in FIG. 7 or FIG. 8. That is, the ground voltage waveform whose potential rises from the true earth leakage position by the commercial power supply flowing into the ground due to poor insulation of the power equipment is due to the pure sine wave or the parasitic voltage containing the power frequency as shown in FIG. The components with the difference of magnitude and magnitude have the synthesized waveform.

As shown in FIG. 3, the commercial power source has a relatively high internal impedance at the ground fault point 207, although the voltage drop through R1 occurs until the ground surface is reached, the ground voltage at the measuring point 135 is as shown in FIG. 6. It has a sine wave characteristic with a pure single power frequency (50 or 60 Hz) that does not include external noise.

In view of this, in the prior art, as shown in FIG. 2, a leakage rate is obtained by determining the ratio of the content of the total voltage value V1 to the power frequency (50 or 60 Hz) voltage value Vf and the voltage which checks whether the earth voltage is actual voltage. However, it is not possible to distinguish where the ground voltage rises due to parasitic voltages (organic and drift voltages).

7 shows an example of parasitic voltage waveforms. Although similar to the 60Hz waveform, which is the power frequency, the content rate is less than 85%, so there is no problem in determining the parasitic voltage. However, in FIG. 8, the content rate is maintained at 85% or more even though the parasitic voltage is not a pure waveform but is a distorted waveform. It's an example of a misunderstanding

FIG. 9 illustrates a method of counting (counting) the number of zero crossings of the ground voltage at the earth leakage point position, and a power frequency and a magnitude of its harmonics after Fourier transform.

FIG. 10 shows a method of counting the number of zero crossings of the ground voltage at the parasitic voltage source embedding position and the signal frequency of the power frequency and its harmonics after Fourier transform.

By counting the number of zero crossings in addition to the content of the earth voltage input as shown in FIGS. 9 and 10, the parasitic voltage as shown in FIG. 7 is true even if the number of zero crossings is counted for five cycles, even though the parasitic voltage of FIG. In the short circuit, the device has 10 zero crossing counts (ZCCs), but the parasitic voltages have more than 10 times of ZCCs so that the input parasitic voltages can be distinguished.

However, in order to determine the true leakage voltage of the waveform as shown in FIG. 7, a ZCC (Zero Crossing Count) that crosses the zero voltage value is counted, but has a ZCC similar to the fundamental frequency, so that an error in the determination may occur. In order to accurately determine the waveform including distortion (not distortion), which is not pure sine wave, the parasitic having the distortion waveform having the power frequency shape as shown in FIG. 7 by counting the number of distortions (DC, Distortion) instead of ZCC as needed. To filter the voltage

Fig. 11 illustrates the distortion count point of the distortion waveform.

FIG. 12 illustrates a method for counting the number of locations where distortion occurs as in FIG. That is, the difference between the current signal value and the previous signal value is calculated so that 1 count is added when the polarity is inverted. FIG. 13 illustrates a DC count work flow for 5 cycles as a flowchart.

As an example according to the present invention, FIG. 28 is a screen 60 for selecting ZCC or DC when determining distortion of a waveform, and the magnitude of the difference value (DC) when DC 62 is selected without selecting ZCC 61. The magnitude of the sample difference to determine the polarity reversal to count) should be set on screen 63. In our example, we can see that it is set to 2,069 sample differences.

23 and 27, it can be seen that the DC count value 48 of the true leakage position 17 and 49 at the parasitic voltage position, and when the DC count number is 8 <DC <28 it was determined as true leakage voltage If it is out of range, it is considered as parasitic voltage and ignored.

In addition, as a result of Fourier transform as shown in FIG. 9, the fundamental frequency component of 60 Hz, which is the power frequency, occupies most of the power leakage point, and is consistent with 85% or more of the conventional method. However, as shown in FIG. On the other hand, other harmonic components including the third harmonic, 180 Hz, can be observed to increase.

Therefore, instead of hardware filtering the input ground voltage signal to improve the accuracy of the existing content, the Fourier transform was used to specify the content, power frequency, and threshold of THD for each harmonic as follows.

The following is a measurement table of power frequencies and odd-numbered harmonic spectral voltage values when Fourier transformed true leakage voltage and parasitic voltage of FIGS. 21 and 25.

Frequency spectrum Voltage value (V) Fundamental frequency (V1) 2.892 Third harmonic (V3) 0.114 5th harmonic (V5) 0.034 7th harmonic (V7) 0.017 9th harmonic (V9) 0.016 Total (Vt) 3.073

Frequency spectrum Voltage value (V) Fundamental frequency (V1) 1.751 Third harmonic (V3) 0.248 5th harmonic (V5) 0.062 7th harmonic (V7) 0.039 9th harmonic (V9) 0.035 Total (Vt) 2.135

Based on the measured values of Table 1 and Table 2, the results of calculating the harmonic distortion rate are as follows.

division True earth leakage voltage Parasitic voltage Threshold Remarks Content rate (V1 / Vt) 94.11% 82.01% 85.5%> THD 4.20% 14.90% <10% THD_F3 3.94% 14.16% <10% THD_F5 1.17% 3.54% <3% THD_F7 0.58% 2.22% <2%

By setting the content and harmonic threshold as shown in Table 3 above, only earth voltage signal within this threshold range was determined as true leakage voltage, and this area was determined as a suspected earth leakage region.

As described above, by measuring the content of the power frequency signal (fundamental frequency) contained in the signal and THD, ZCC or DC as described above, the method is not limited to a method and apparatus for finding a power supply location, but also in other diagnostic technologies. It can also be used as a technique for finding the location of poor insulation.

FIG. 14 is a diagram illustrating a short circuit suspecting section exploration configuration of a ground fault detecting apparatus 101 capable of freely moving on an arbitrary land and determining a suspected short circuit section without transmitting (injecting) a separate ground fault detecting signal according to the present invention. . Unlike before, Fourier transform is used without using a hardware filter to obtain the voltage (V1) and the total voltage (Vt) of the fundamental frequency (60 Hz) to obtain the content rate, THD, and ZCC or DC to determine the distortion of the waveform. To count.

FIG. 15 is a flowchart illustrating a leakage suspected section exploration project functioning as a function of FIG. 14.

FIG. 16 is a ground fault detection apparatus capable of transmitting (injecting) a ground fault detection signal to a power facility (power line) within a section determined as the ground fault suspect section according to the present invention, moving within a predetermined position, and determining a ground fault position ( 131 shows an earth leakage point exploration configuration. When the ground fault detection is performed, the ground fault detection voltage 133 and the current signal are injected into the power lines 202 and 203 in the suspected short circuit section, and the magnetic field signals 141 and 142 generated by the ground fault detection current signal flowing through the power line. After receiving on the ground and moving along the buried paths of the power lines 202 and 203, the ground fault detection device 131 is contacted to the ground (135 and 136) on the ground to measure the ground voltage to perform a ground fault detection to find the position of the ground fault point. At this time, the magnetic field signals 141 and 142 used in the path detection are received and measured according to the occurrence time of the earth leakage detection voltage pulse signal 140 to be generated next, and the true value is analyzed by analyzing the coding value included in the earth leakage detection voltage pulse signal 140. If the coding values match, the maximum detection position of the ground fault detecting voltage pulse signal 140 is determined as the ground fault point.

FIG. 17 is a flowchart illustrating an electrical leak detecting operation task using the configuration of FIG. 16.

Compared with the prior art, in the present invention, in order to increase the accuracy of the content rate for determining a short circuit, the content rate was calculated by using a ratio of the magnitude and the total voltage of the power frequency components by hardware filtering, but in the present invention, the power frequency after Fourier transform Comparing total harmonics, the content rate was calculated to improve accuracy, and the ability to determine the degree of distortion of the waveform was added.

In addition, in the previous technology, the parasitic voltage filtering function was omitted under the assumption that there was only a true leakage power when detecting an earth leakage point within a suspected earth leakage section, and only the signal size included in the earth leakage detection voltage signal was measured. In the ground fault detecting mode, it was first confirmed whether or not the ground voltage of the input ground voltage was true, and the ground fault alarm was generated according to the ground fault detecting result only when it was determined as true ground fault voltage.

18 shows the results of the exploration of the suspected short circuit area according to the present invention by location. In the non-leakage point, the ground voltage (Vrms), content rate, ZCC / DC and THD do not reach the threshold, and it can be seen that an alarm occurs exactly at the leakage point.

19 shows the results of the earth leakage point exploration by position. The earth leakage detection signal is detected at the earth leakage point together with the red earth leakage detection signal to detect the maximum position so that it can be judged as the earth leakage point.If the earth potential rises above 500mV as shown on the right side of the drawing, Among the algorithms for filtering voltage, the leakage alarm does not occur because the distortion counter and the third harmonic THD do not pass the threshold value. Therefore, even if the leakage detection signal is detected, it is determined to be not true leakage and is ignored.

Next will be described the screen configuration of the ground fault detecting apparatus according to the present invention.

20 to 23 are screens showing the results of the measurement at the true earth leakage voltage location. FIG. 20 shows the leakage suspected section detection screen 29, V1 21 is the sum of all harmonic voltages, Vf 22 is the fundamental frequency voltage of 60 Hz which is the power frequency, and R 23 shows the content rate. In addition, Z (24) is the number of ZCC, and 25, 26, 27, and 28 show whether the THD and the odd harmonic THD do not exceed the threshold. In other words, all four are marked in red to meet the threshold conditions. If all of these conditions are met, the user determines that a true leakage is present near the location and performs the next step, the earth leakage test.

FIG. 21 is a graph illustrating voltage values of spectra of Fourier transform results when a button 31 of FIG. 20 is pressed. It can be seen that the fundamental frequency (5) voltage is 2.8926V (2), and the total voltage is 3.07V (1). When calculating this, the content rate (4) is 94% and although it does not show all, the apparatus judges that all conditions are satisfied, and is generating the ground fault alarm (3).

22 is a waveform screen showing when the waveform button 32 of FIG. 20 is pressed. The shape of the waveform of the ground voltage to be measured can be observed, and the content rate, ZCC, and ground fault alarm can be confirmed.

FIG. 23 is a screen captured at the maximum point of the earth leakage signal after it is determined as a suspected earth leakage section at the same place as in FIG. The earth leakage signal value indicates 4,625 (41) and indicates coding values 56 and 57. Other matters are the same as those of FIG. 20 to determine the true earth leakage voltage.

24 to 27 are examples of screens showing the results of measuring parasitic voltages. FIG. 24 is a screen 29 for detecting an earth leakage suspect interval by measuring a ground voltage whose potential is increased by parasitic voltage, and the rest of the description is the same as in FIG. 20. However, the total earth voltage V1 (21) does not reach the threshold value of 500 mV, and the content rate R (23) does not reach 85%. The distortion count is 49 times, and most of the THD does not satisfy the threshold.

FIG. 25 shows the result of Fourier transforming the ground voltage in FIG. 24. It can be seen that the content rate (4) is 82% and the value of the fundamental frequency spectrum voltage (5, 2) is relatively low and the value of the third harmonic voltage (6) is increased, and the electric leakage alarm (3) does not satisfy all conditions. It is not occurring.

FIG. 26 shows the ground voltage waveform of FIG. 24. It can be seen that the waveform is not a pure sine wave, but a waveform containing a lot of distortion. The DC count can be easily determined without looking.

FIG. 27 is a screen captured at a maximum point of an earth leakage signal after connecting an exploration signal device to a power line to determine whether a misjudgment occurs in the same manner as in the previous technology, although it is not determined as an earth leakage suspect section at the place of FIG. 24. The earth leakage signal value indicates 4,685 (41) due to parasitic voltage, but it is not displayed because the coding value does not match, and it can be seen that the DC count is 49 and the content is 80%. Even if the ground fault voltage signal is detected, the ground fault signal is ignored because no other ground fault voltage determination logic is passed, and the ground fault alarm is not generated to prevent the ground fault point.

28 is a screen for selecting to count ZCC or DC in order to determine distortion and the like of the ground voltage waveform.

As described above, the present invention is a technique for finding a position in which a part of electric power flows out to the ground and raises the ground voltage as a poor insulation of the power equipment that transmits or stores the commercial power. Analyze and compare the composition of voltages by harmonics, and also compare the degree of distortion of the waveform to detect the leakage point only when it is determined to be a true earth leakage voltage, and repair according to the result. There is an advantage that can be prevented.

29 is a block diagram of an electrical leak detecting apparatus according to another exemplary embodiment.

Referring to FIG. 29, when the earth leakage detecting apparatus 1000 satisfies a preset condition by measuring a ground voltage, the ground fault detecting apparatus 1000 may determine that the measured ground voltage is caused by a short circuit of the power line. In detail, in a Neutral Multiple Ground Neutral (MEN) environment having a plurality of power line PENs (Protective Earthed Neutral) that ground the neutral line, the ground fault detecting apparatus 1000 may measure the ground voltage at any power line PEN. . When the measured ground voltage satisfies a preset condition, the ground fault detecting apparatus 1000 may determine a ground fault suspect region as a ground fault occurs in a power line embedded around the power line PEN measuring the ground voltage. When the suspected ground fault zone is determined, the ground fault detection apparatus 1000 may receive a magnetic field signal generated from the exploration current generator to measure the ground voltage along a path in which the power line in the ground fault suspect zone is embedded. The ground voltage measured along the buried path includes a ground fault detection voltage signal generated from a ground fault detection voltage signal generator, and the ground fault detection device 1000 is a ground fault that is a point at which a ground fault occurs in a power line based on the ground fault detection voltage signal. You can judge the point. The ground fault detecting apparatus 1000 includes a ground voltage measuring unit 1110, an ADC unit 1120, an effective value calculating unit 1130, a Fourier transform unit 1140, a content rate calculating unit 1150, a harmonic distortion rate calculating unit 1160, and zero. Crossing calculation unit 1170, distortion calculation unit 1180, earth leakage suspected zone determination unit 1190, magnetic field signal receiver 1210, earth leakage detection voltage signal receiver 1220, power line buried path search unit 1230, earth leakage point The determination unit 1240 and the display unit 1300 may be included.

The ground voltage measuring unit 1110 of the ground fault detecting apparatus 1000 will be described in detail with reference to FIG. 30.

30 is an illustration for explaining a method of measuring a ground voltage in another embodiment of the present invention.

Referring to FIG. 30, the ground voltage measuring unit 1110 may measure the ground voltage. Specifically, the ground voltage measuring unit 1110 is in parallel with an electrode connected to a measuring point a which is an arbitrary point on the earth surface, an electrode connected to a measuring point b which is an arbitrary point on the earth surface different from the measuring point a, a measuring point a and a measuring point b in parallel. It may include a voltage measuring unit for measuring the voltage between the connected resistor array and the resistor array.

More specifically, when an electric leakage of the power line occurs in the ground, the electric leakage current is designed to return to the electric power line PEN at the shortest distance. The ground voltage measuring unit 1110 is an AC commercial power source in proportion to the magnitude of the leakage current of the AC commercial power source (AC 60 Hz 220V in the case of Korea) and the earth resistance (Rg) according to the insulation failure of the voltage supply (phase line) for power supply. It is possible to measure the ground voltage caused by the leakage of

For example, as shown in FIG. 30, the ground potential a for each position due to an earth leakage of the AC commercial power is determined according to the earth resistance (Rg) value from the position a and the position b to the power line PEN by the ground current of the AC commercial power. And earth potential b values are distributed in the soil. The earth leakage detecting apparatus 1000 may not directly measure earth potentials a and b for each position of the soil in the ground to detect an earth leakage power, but instead measure the AC commercial power earth potential at the measurement points a and b on the ground surface. .

The ground potentials a and b of the ground are affected by the resistance Rp, which includes land resistance, pavement (asphalt) resistance, and contact resistance between the electrode and the ground until reaching the measurement points a and b on the ground.

As shown in the AC commercial power potential distribution graph at the top of the figure, the ground potentials a and b for each position under the ground pass through two Rp (2 x Rp), and the potential value is changed to reach the measurement points a and b.

As described above, there is a problem in that the potential value is changed at the ground surface due to the influence of the resistor Rp, and the distance between the electrodes is short, so that it is difficult to distinguish the amplitude of the potential difference value. In order to solve this problem, the electrode is connected with the power line PEN and the surface of the equipotentially bonded metal body (for example, manhole cover) as the measuring point a. That is, in a structure having a power line PEN, a conductive metal such as a manhole cover is bonded with a grounded neutral wire and constructed to maintain an equipotential without a potential difference between conductors, and the ground voltage measuring unit 1110 measures the neutral line voltage. Measure the ground voltage with

In this case, when the neutral-bonded neutral voltage in the neutral grounded power line PEN is used as the measurement reference voltage of the ground voltage, the influence of the resistance Rp at the measuring point a can be reduced, so that the ground voltage having a stable and large amplitude potential difference value can be measured. Can be. In addition, as in the previous technology, there is no need to enter and exit the structure in which the power line PEN is installed, thereby improving work environment and saving work time. The above-described method for measuring the ground voltage is only an example, and the present disclosure is not limited thereto.

Referring back to FIG. 29, the ADC unit 1120 of the ground fault detecting apparatus 1000 samples the measured ground voltage and converts the measured ground voltage into a digital value.

In detail, the ground voltage measured by the ground voltage measuring unit 1110 has an analog value, and the ADC unit 1120 samples the measured ground voltage value and converts the measured ground voltage value into a digital value. More specifically, the ADC unit 1120 may perform sampling to generate a sample by cropping the ground voltage measured by the ground voltage measuring unit 1110 by a predetermined time unit. In addition, the ADC unit 1120 may convert an analog value of the ground voltage included in each sample into a digital value.

The RMS value calculator 1130 of the ground fault detecting apparatus 1000 calculates an RMS value of the ground voltage converted into a digital value.

The ground voltage generated by the leakage of AC commercial power has a value larger than the ground voltage generated by induced voltage or stray voltage parasitic around power line. Therefore, when the effective value of the ground voltage calculated by the effective value calculator 1130 has a value larger than a preset threshold voltage value (for example, 500 mV), the measured ground voltage is generated by the leakage of the AC commercial power supply. It can be judged.

The Fourier transform unit 1140 of the ground fault detecting apparatus 1000 performs Fourier transform on the measured ground voltage based on the effective value of the ground voltage to calculate a voltage for each harmonic component that is an integer multiple of the fundamental frequency—the power frequency of the AC commercial power source. can do.

Even if the ground voltage measured by the ground fault detecting apparatus 1000 is caused by a short circuit of the power line, the ground fault component may include harmonic components due to disturbances such as parasitic voltage and ground resistance. Therefore, since it is difficult to determine whether the ground voltage measured by the harmonic component is caused by the leakage of the AC commercial power supply, it is necessary to analyze how much the ground voltage contains the harmonic component.

The Fourier transform unit 1140 transforms the measured ground voltage by Fourier transform, and sets the fundamental frequency to 60 Hz, which is the power frequency of AC commercial power (AC 60 Hz 220 V in Korea), and a harmonic that is an integer multiple of the fundamental frequency and the voltage value having the fundamental frequency. The voltage value for each component can be calculated.

As described above, referring back to FIG. 9 and FIG. 10, the Fourier transformer may calculate the voltage value for each harmonic component that is an integer multiple of the fundamental frequency. As shown in FIG. 9, the measured ground voltage contains more voltage having a fundamental frequency of 60 Hz than a voltage having an integer multiple of the fundamental frequency such as 120 Hz, 180 Hz, 240 Hz, which are harmonic components, and is less affected by harmonics due to disturbance. Able to know. Therefore, the measured ground voltage may be determined to be caused by the leakage of the AC commercial power supply. On the other hand, since the measured ground voltage shown in FIG. 10 contains a large number of voltages having integral multiples of fundamental frequencies such as 120 Hz, 180 Hz, and 240 Hz, which are harmonic components, it can be seen that the harmonic effects due to disturbance and the like are much affected. Therefore, the measured ground voltage cannot be determined to be caused by the leakage of the AC commercial power supply.

Based on the voltage value of each harmonic component converted by the Fourier transform unit 1140, the content rate calculator 1150 may calculate a voltage content ratio of the fundamental frequency to the voltage obtained by adding the voltages of the harmonic components. In addition, based on the voltage value of each harmonic component, the harmonic distortion calculation unit 1160 may calculate a total harmonic distortion and a harmonic distortion factor.

The content rate calculator 1150 of the electrical leak detecting apparatus 1000 may calculate a voltage content rate V1 / Vt of a fundamental frequency to a voltage obtained by summing voltages of harmonic components based on voltages of harmonic components.

As the content rate calculated by the content rate calculator 1150 is higher, it indicates that the measured earth voltage has more components with respect to the fundamental frequency. Therefore, when the content rate exceeds a preset content rate (eg, 85%), it can be determined that the measured ground voltage is caused by the leakage of the AC commercial power supply.

As mentioned above, referring back to Tables 1 and 2, in Table 1, the content of voltage having a fundamental frequency component relative to the total voltage exceeds a predetermined content (e.g., 85%), but in Table 2 the total voltage The content rate of the voltage having a contrast fundamental frequency component does not exceed a preset content rate (eg, 85%). Therefore, the ground voltage measured in Table 1 may be determined to be caused by the leakage of AC commercial power. The method of determining that the ground voltage is caused by an electric leakage based on the above-described content is merely an example, and the present disclosure is not limited thereto.

The harmonic distortion calculator 1160 of the ground fault detecting apparatus 1000 may calculate a total harmonic distortion and a harmonic distortion factor based on the harmonic component voltage.

The total harmonic distortion can be calculated by the above equation (3). The distortion factor for each harmonic component may be calculated by Equation 4 described above. The higher the total harmonic distortion rate and the distortion rate for each harmonic component, the more harmonic components are included.

When the total harmonic distortion calculated by the harmonic distortion calculation unit 1160 is less than the preset distortion, and the harmonic component distortion distortion is less than the preset distortion, it may be determined that the measured ground voltage is less affected by harmonics. If it is determined that the measured earth voltage is less affected by harmonics, it is possible to determine that the earth voltage is caused by the leakage of AC commercial power by calculating the effective value, the content rate and the number of zero crossings based on the measured earth voltage. Accuracy and reliability.

The zero crossing calculation unit 1170 of the ground fault detecting apparatus 1000 may calculate the number of zero crossings in which the ground voltage converted to the digital value passes the zero voltage during a preset time T1. have. Here, the preset time T1 may be a time that is a preset integer multiple of the period of the AC commercial power source.

The zero crossing calculation unit 1170 may calculate the number of zero crossings that pass through the zero voltage when the polarity of the ground voltage changes during the preset time T1.

The zero crossing count calculated by the zero crossing calculation unit 1170 indicates that the measured ground voltage contains a lot of fundamental frequency components which are the power frequencies of the AC commercial power, and the measured ground voltage is caused by the leakage of the AC commercial voltage. Can be judged.

For example, the preset time T1 may be set to five times the period of the AC commercial power source. In this case, the number of zero crossings of the AC commercial power source is ten times. When the number of zero crossings of the measured earth voltage is 10, the earth voltage contains a large amount of 60 Hz, and it may be determined that the measured earth voltage is caused by the leakage of the AC commercial voltage. On the other hand, when the number of zero crossings of the measured earth voltage exceeds 10 times, the earth voltage contains a lot of frequency components larger than 60 Hz, which can be judged as the earth voltage generated by the effects of harmonics or parasitic voltages. have.

In addition, as described above, referring back to FIG. 7, the ground voltage is shorted when the measured ground voltage is similar to the 60 Hz waveform which is the power frequency, but the content is less than a predetermined content (eg, 85%). It may be determined that it is caused by a parasitic voltage rather than by a. Referring back to FIG. 8, although the measured earth voltage exceeds a preset content rate (eg, 85%), it does not resemble a 60 Hz waveform, which is a power frequency, and the AC commercial power supply for the trimmed time T1. Since the number of zero crossings exceeds the number of zero crossings of the ground voltage, it may be determined as the ground voltage generated by the influence of harmonics or a parasitic voltage.

The method of determining that the ground voltage is caused by the leakage of the AC commercial voltage based on the number of zero crossings described above is merely an example, and the present disclosure is not limited thereto.

The distortion calculation unit 1180 of the ground fault detecting apparatus 1000 may calculate the number of distortions, which is the number of distortions caused by harmonics in the measured ground voltage during a preset time T1. Here, the preset time T1 may be a time that is a preset integer multiple of the period of the AC commercial power source. More specifically, the distortion calculation unit 1180 may receive the ground voltage converted into a digital value for each sample from the ADC unit 1120 . In addition, the distortion calculation unit 1180 may output the difference of the ground voltage measurement value (digital value) in the first sample and the second sample which are continuous to each other as the first change amount. In addition, the distortion calculation unit 1180 may output the difference of the ground voltage measurement value (digital value) in the second sample and the third sample that is continuous as the second change amount. Accordingly, the distortion calculation unit 1180 may determine that the distortion has occurred if the first change amount and the second change amount have different polarities, and may calculate the number of distortions. That is, the distortion calculation unit 1180 is based on the ground voltage converted into a digital value for each sample included in the preset time (for example, time T1 which is a predetermined integer multiple of the period of the AC commercial power supply) from the ADC unit 1120. The number of distortions by which the polarity of the change amount of the ground voltage is changed can be estimated .

A detailed method of calculating the number of distortions by the distortion calculation unit 1180 will be described with reference to FIGS. 31 and 32.

31 is an illustration for explaining a method for calculating the number of distortions according to another embodiment of the present invention.

Referring to FIG. 31, the distortion calculation unit 1180 may include a polarity and a second polarity of the first change amount of the digital value of the first earth voltage sampled and converted and the digital value of the second earth voltage sampled and converted after the next sampling period. When the digital value of the ground voltage and the polarity of the second change amount of the digital value of the third ground voltage converted by sampling after the next sampling period are different from each other, it is determined that the distortion occurs due to harmonics, and the number of distortions can be calculated. have. For example, when the digital value of the first ground voltage is 50 mV and the digital value of the next sampled second ground voltage is 53 mV, the first change amount is positive (+) 3 mV and the polarity is positive. When the digital value of the next sampled third ground voltage is 52mV, the second change amount is negative (-) 1mV and the polarity is negative. In this case, the polarity of the first change amount and the polarity of the second change amount are different, and it is determined that distortion due to harmonics has occurred, and the number of distortions can be calculated.

32 is a flowchart illustrating a method of calculating the number of distortions according to another embodiment of the present invention.

Referring to FIG. 32, when the polarity of the first change amount and the second change amount are different from each other, the distortion calculation unit 1180 may calculate the number of distortions once. When the total number of distortions calculated during the preset time T1 is less than the preset number of distortions, it is determined that the measured ground voltage is less affected by harmonics. If it is determined that the measured earth voltage is less affected by harmonics, it is possible to determine that the earth voltage is caused by the leakage of AC commercial power by calculating the effective value, the content rate and the number of zero crossings based on the measured earth voltage. Accuracy and reliability.

Referring back to FIG. 29, the earth leakage suspected zone determining unit 1190 of the earth leakage detecting apparatus 1000 may determine at least any one of the effective value of the ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, the number of zero crossings, and the number of distortions. Based on one, it can be determined that the ground voltage is caused by the leakage of the AC commercial power source, and based on the determined result, the region where the ground voltage is measured can be determined as the suspected short circuit region.

More specifically, the earth leakage suspected area determining unit 1190 may include an effective value of the ground voltage exceeding a preset threshold voltage value, a voltage content exceeding a preset voltage content, and a total harmonic distortion rate less than a preset total harmonic distortion rate. When the distortion rate per harmonic component is less than the preset distortion ratio for each harmonic component, the number of zero crossings matches the preset number, and the number of distortions is less than the preset number, the ground voltage may be generated by the leakage of AC commercial power. You can judge. The above-described method of determining the suspected short circuit area is merely an example. The present disclosure is not limited thereto.

When the earth leakage suspected area determining unit 1190 determines that the ground voltage measured by the power line PEN is caused by a short circuit of the AC commercial power supply, the ground fault point determining unit 1240 is a power line embedded in the ground of the power line PEN which measured the ground voltage. By following the path of, the point where the actual short circuit occurred in the power line can be determined as the short circuit point.

The magnetic field signal receiver 1210 of the ground fault detecting apparatus 1000 may receive a magnetic field signal generated from the sensing current generator.

As described above, the exploration current generating device injects a current signal to the power line and the center line in the suspected short circuit area, and the magnetic field signal receiving unit 1210 receives a magnetic field signal generated by the sensing current flowing through the power line and the center line in the ground can do. More specifically, the exploration current generating device may be connected to a power line and measure a power frequency flowing through the power line. In addition, the exploration current generating device may generate a magnetic field signal, that is, an exploration current for the earth leakage point exploration, and transmit it on the power line. In addition, the magnetic signal receiver 1210 may include a magnetic field sensor to receive the magnetic field signal.

The magnetic field signal receiver 1210 may include a plurality of magnetic field sensors and may receive the magnetic field polarity and the magnitude of the magnetic field signal.

The power line embedding path search unit 1230 of the ground fault detecting apparatus 1000 may search a path of the power line embedded in the suspected short circuit area based on the received magnetic field signal.

More specifically, the power line embedding path search unit 1230 may monitor the magnitude of the magnetic field signal received by the magnetic signal receiver (). The point at which the magnitude of the received magnetic field signal is the maximum point according to the position of the ground fault detecting apparatus may be determined as one point of the path of the power line. Here, the point where the magnitude of the magnetic field signal is the maximum point may mean a point where the magnitude of the magnetic field signal measured on the same line is maximum when the earth leakage detecting apparatus is moved in a straight line. The power line embedding path search unit 1230 may determine a path of the power line according to the magnitude of the magnetic field signal having the same magnitude. Further, according to an embodiment, the power line embedding path search unit 1230 determines the path of the power line by connecting another high maximum magnetic field signal size measurement position of the surroundings based on one point where the measured value of the magnetic field signal is the maximum. You may. For example, the power line embedding path search unit 1230 may determine the point where the magnetic field signal size is the maximum point as the embedded power line path. Also, the power line embedding path search unit 1230 may search for the direction of the path in which the power line is embedded based on the magnetic field signal polarity.

The earth leakage detection voltage signal receiver 1220 of the earth leakage detection apparatus 1000 may receive an earth leakage detection voltage signal generated from the earth leakage detection voltage signal generator.

As described above, the ground fault detection voltage signal generator transmits a ground fault detection voltage signal, which is a DC pulse voltage, to the power line. When the power line is shorted, the ground fault detection voltage signal is included in the AC commercial power supply to measure the ground voltage. Since the ground voltage measured by the ground voltage measuring unit 1110 also includes harmonic components, it is difficult to determine whether the pulse voltage component is an earth leakage detection voltage signal or a harmonic component in the ground voltage. Therefore, the earth leakage detection voltage signal generator transmits the earth leakage detection voltage signal after a predetermined time from the time when the detection current generation device transmits the detection current. Based on the time when the magnetic field signal receiving unit 1210 receives the magnetic field signal generated by the detection current received, the ground fault detecting voltage signal receiving unit 1220 detects the short circuit voltage component from the ground voltage measured after a preset time. It can be detected by a voltage signal.

The ground fault point determiner 1240 of the ground fault detection apparatus 1000 may determine the ground fault point of the embedded power line based on the ground fault detection voltage signal.

The ground fault point determiner 1240 sets a logic value according to whether the ground fault detection voltage signal is received, coincides with the set logic value and the logic value of the ground fault detection voltage signal generated by the ground fault detection voltage signal generator, and the ground fault detection voltage. The point where the signal has the maximum value may be determined as the ground fault point. For example, when the ground fault point determiner 1240 receives the magnetic field signal and receives the ground fault detection voltage signal after a preset time, the ground fault point determiner 1240 may output a logic value “1”. When the ground fault detecting unit 1240 receives the ground fault detection voltage signal, the ground fault point determiner 1240 may output a logic value “1” and determine that the power line is short. In addition, when the ground fault point determiner 1240 outputs a logic value “1”, the ground fault point may determine a point at which the magnitude of the ground fault detection voltage signal is a maximum value. In addition, when the earth leakage point determiner 1240 receives the magnetic field signal and fails to receive the earth leakage detection voltage signal after a preset time, the earth leakage point determiner 1240 may output a logic value “0”. In addition, when the ground fault determining unit 1240 does not receive the ground fault detection voltage signal, the ground fault point determiner 1240 may output a logic value “0” and determine that the corresponding power line is not shorted. The above description of the operation of the ground fault point determiner 1240 is merely an example, and the present disclosure is not limited thereto.

A detailed description of the earth leakage point determiner 1240 moving along the power line embedding path and determining the earth leakage point of the power line will be described with reference to FIGS. 33 and 34.

33 is a diagram illustrating a protocol for receiving a magnetic field signal and receiving a short circuit detection voltage signal according to another embodiment of the present invention.

For example, referring to FIG. 33, when the magnetic signal receiver 1210 receives a magnetic field signal '0101000' having a discontinuous characteristic generated from an exploration current generator, the power line embedding path search unit 1230 is a magnetic field. Set to the signal start time. The power line embedding path searching unit 1230 searches the power line embedding path based on the magnetic field signal polarity and magnitude by measuring the magnetic field signal value at intervals of power frequency cycles after the magnetic field signal start time. The earth leakage detecting apparatus 1000 measures earth voltage at a ground on a power line embedding path and moves along the path. The ground fault detection voltage signal receiver 1220 receives a ground fault detection voltage signal from a ground voltage measured on a path in which a power line is embedded. The ground fault point determiner 1240 analyzes a logic value included in the ground fault detection voltage signal, compares the magnitude of the ground fault detection voltage signal when the logic value is '1', and determines a point having the maximum value of the ground fault detection voltage signal as the ground fault point. do.

34 illustrates an example of a relationship between a notification of start time of a ground fault detection voltage signal and a time at which the ground fault detection voltage signal is measured according to another embodiment of the present invention.

Referring to FIG. 34, the three-phase power supplies each have a 120 degree phase difference, and the sinusoidal voltage waveform is repeated. In the case where the exploration current generator transmits the detection current signal to the C-phase power line, the earth leakage detection voltage signal generator transmits the earth leakage detection voltage signal to the A-phase power line having a 120-degree phase. The earth leakage detection voltage signal is transmitted after a preset time (for example, 1/3 cycle after the time when the probe current signal is transmitted) from the time when the probe current signal is transmitted. The probe current signal generates a magnetic field signal, and when the magnetic field signal receiver 1210 receives the magnetic field signal, the earth leakage detection voltage signal receiver 1220 is set in advance than the time when the magnetic field signal receiver 1210 receives the magnetic field signal. The earth leakage detection voltage signal is received after a time (eg, 1/3 cycle after the time when the probe current signal is transmitted).

The display unit 1300 of the ground fault detecting apparatus 1000 may display whether the measured ground voltage is caused by a short circuit of AC commercial power.

Referring to FIGS. 20 to 28 again, as described above, the display unit 1300 may display a voltage magnitude obtained by adding the voltage magnitude of the power frequency and the voltage for each harmonic component. In addition, the display unit 1300 may display the measured content of the ground voltage, the number of zero crossings, and the number of distortions. In addition, the display unit 1300 may display the magnitude of the voltage for each harmonic component, and may display whether the distortion ratio for each harmonic component is less than a preset distortion ratio through color separation. In addition, the display unit 1300 may display a logic value of the ground fault detection voltage signal, and display a power line of the grounded phase.

35 is a flowchart of a method of determining a suspected short circuit region according to another embodiment of the present invention.

The earth leakage detecting apparatus 1000 may measure the ground voltage (S1101). Specifically, in the case where a power line leakage occurs in the ground, the current leakage current is designed to be fed back to the power line PEN at the shortest distance. The earth leakage detecting apparatus 1000 is a power supply of the AC commercial power in proportion to the magnitude of the earth current (Rg) of the AC commercial power supply (AC 60 Hz 220V in the case of Korea) and the ground resistance (Rg). The ground voltage caused by a short circuit can be measured.

The electrical leak detecting apparatus 1000 samples the measured ground voltage and converts the measured ground voltage into a digital value (S1102).

In detail, the ground voltage measured by the ground fault detecting apparatus 1000 has an analog value, and the ground fault detecting apparatus 1000 samples the measured ground voltage value and converts the measured ground voltage value into a digital value.

The electrical leak detecting apparatus 1000 calculates an effective value of the ground voltage converted into a digital value (S1103).

The ground voltage generated by the leakage of AC commercial power has a value larger than the ground voltage generated by induced voltage or stray voltage parasitic around power line. Therefore, when the effective value of the ground voltage calculated by the ground fault detecting apparatus 1000 has a value larger than a preset threshold voltage value (for example, 500 mV), the measured ground voltage is generated by the leakage of the AC commercial power supply. It can be judged.

The earth leakage detecting apparatus 1000 may calculate a voltage for each harmonic component that is an integer multiple of the fundamental frequency—the power frequency of the AC commercial power source—by Fourier transforming the measured ground voltage based on the effective value of the ground voltage (S1104).

Even if the ground voltage measured by the ground fault detecting apparatus 1000 is caused by a short circuit of the power line, the ground fault component may include harmonic components due to disturbances such as parasitic voltage and ground resistance. Therefore, since it is difficult to determine whether the ground voltage measured by the harmonic component is caused by the leakage of the AC commercial power supply, it is necessary to analyze how much the ground voltage contains the harmonic component.

The earth leakage detection apparatus 1000 performs Fourier transform on the measured ground voltage to set a fundamental frequency of 60 Hz, which is a power frequency of an AC commercial power supply (AC 60 Hz 220 V in the case of Korea), and a harmonic that is an integer multiple of a fundamental frequency and a voltage value having a fundamental frequency. The voltage value for each component can be calculated.

As described above, referring back to FIG. 9 and FIG. 10, the Fourier transformer may calculate the voltage value for each harmonic component that is an integer multiple of the fundamental frequency. As shown in FIG. 9, the measured ground voltage contains more voltage having a fundamental frequency of 60 Hz than a voltage having an integer multiple of the fundamental frequency such as 120 Hz, 180 Hz, 240 Hz, which are harmonic components, and is less affected by harmonics due to disturbance. Able to know. Therefore, the measured ground voltage may be determined to be caused by the leakage of the AC commercial power supply. On the other hand, since the measured ground voltage shown in FIG. 10 contains a large number of voltages having integral multiples of fundamental frequencies such as 120 Hz, 180 Hz, and 240 Hz, which are harmonic components, it can be seen that the harmonic effects due to disturbance and the like are much affected. Therefore, the measured ground voltage cannot be determined to be caused by the leakage of the AC commercial power supply.

The electrical leak detecting apparatus 1000 may calculate a voltage content ratio V1 / Vt of a fundamental frequency to a voltage obtained by summing voltages of harmonic components based on voltages of the harmonic components (S1105).

As the content rate calculated by the ground fault detecting apparatus 1000 is higher, it indicates that the measured ground voltage has a lot of components with respect to the fundamental frequency. Therefore, when the content rate exceeds a preset content rate (eg, 85%), it can be determined that the measured ground voltage is caused by the leakage of the AC commercial power supply.

As mentioned above, referring back to Tables 1 and 2, in Table 1, the content of voltage having a fundamental frequency component relative to the total voltage exceeds a predetermined content (e.g., 85%), but in Table 2 the total voltage The content rate of the voltage having a contrast fundamental frequency component does not exceed a preset content rate (eg, 85%). Therefore, the ground voltage measured in Table 1 may be determined to be caused by the leakage of AC commercial power. The method of determining that the ground voltage is caused by an electric leakage based on the above-described content is merely an example, and the present disclosure is not limited thereto.

The electrical leak detection apparatus 1000 may calculate a total harmonic distortion and a harmonic distortion factor based on the voltage for each harmonic component (S1106).

The total harmonic distortion can be calculated by the above equation (3). The distortion factor for each harmonic component may be calculated by Equation 4 described above. The higher the total harmonic distortion rate and the distortion rate for each harmonic component, the more harmonic components are included.

When the total harmonic distortion rate calculated by the ground fault detection apparatus 1000 is less than the preset distortion rate, and the harmonic component variation distortion rate is less than the preset distortion rate, it may be determined that the measured ground voltage is less affected by harmonics. If it is determined that the measured earth voltage is less affected by harmonics, it is possible to determine that the earth voltage is caused by the leakage of AC commercial power by calculating the effective value, the content rate and the number of zero crossings based on the measured earth voltage. Accuracy and reliability.

The earth leakage detecting apparatus 1000 may calculate the number of zero crossings in which the ground voltage converted to the digital value passes the zero voltage during the preset time T1 (S1106). Here, the preset time T1 may be a time that is a preset integer multiple of the period of the AC commercial power source.

The earth leakage detecting apparatus 1000 may calculate the number of zero crossings that pass the zero voltage when the polarity of the ground voltage changes during the preset time T1.

The zero crossing count calculated by the ground fault detecting apparatus 1000 is determined that the measured ground voltage contains a lot of fundamental frequency components which are the power frequencies of the AC commercial power, and the measured ground voltage is caused by the leakage of the AC commercial voltage. Can be.

For example, the preset time T1 may be set to five times the period of the AC commercial power source. In this case, the number of zero crossings of the AC commercial power source is ten times. When the number of zero crossings of the measured earth voltage is 10, the earth voltage contains a large amount of 60 Hz, and it may be determined that the measured earth voltage is caused by the leakage of the AC commercial voltage. On the other hand, when the number of zero crossings of the measured earth voltage exceeds 10 times, the earth voltage contains a lot of frequency components larger than 60 Hz, which can be judged as the earth voltage generated by the effects of harmonics or parasitic voltages. have.

In addition, as described above, referring back to FIG. 7, the ground voltage is shorted when the measured ground voltage is similar to the 60 Hz waveform which is the power frequency, but the content is less than a predetermined content (eg, 85%). It may be determined that it is caused by a parasitic voltage rather than by a. Referring back to FIG. 8, although the measured earth voltage exceeds a preset content rate (eg, 85%), it does not resemble a 60 Hz waveform, which is a power frequency, and the AC commercial power supply for the trimmed time T1. Since the number of zero crossings exceeds the number of zero crossings of the ground voltage, it may be determined as the ground voltage generated by the influence of harmonics or a parasitic voltage.

The method of determining that the ground voltage is caused by the leakage of the AC commercial voltage based on the number of zero crossings described above is merely an example, and the present disclosure is not limited thereto.

The electrical leak detecting apparatus 1000 may calculate the number of distortions, which is the number of distortions caused by harmonics in the measured ground voltage during the preset time T1 (S1108). Here, the preset time T1 may be a time that is a preset integer multiple of the period of the AC commercial power source.

A detailed method of calculating the number of distortions by the ground fault detecting apparatus 1000 will be described with reference to FIGS. 31 and 32.

31 is an illustration for explaining a method for calculating the number of distortions according to another embodiment of the present invention.

Referring to FIG. 31, the earth leakage detecting apparatus 1000 may include a polarity and a second polarity of the first change amount of the digital value of the first earth voltage sampled and converted and the digital value of the second earth voltage sampled and converted after the next sampling period. When the digital value of the ground voltage and the polarity of the second change amount of the digital value of the third ground voltage converted by sampling after the next sampling period are different from each other, it is determined that the distortion occurs due to harmonics, and the number of distortions can be calculated. have. For example, when the digital value of the first ground voltage is 50 mV and the digital value of the next sampled second ground voltage is 53 mV, the first change amount is positive (+) 3 mV and the polarity is positive. When the digital value of the next sampled third ground voltage is 52mV, the second change amount is negative (-) 1mV and the polarity is negative. In this case, the polarity of the first change amount and the polarity of the second change amount are different, and it is determined that distortion due to harmonics has occurred, and the number of distortions can be calculated.

32 is a flowchart illustrating a method of calculating the number of distortions according to another embodiment of the present invention.

Referring to FIG. 32, the earth leakage detecting apparatus 1000 may calculate the number of distortions once when the polarity of the first change amount and the polarity of the second change amount are different. When the total number of distortions calculated during the preset time T1 is less than the preset number of distortions, it is determined that the measured ground voltage is less affected by harmonics. If it is determined that the measured earth voltage is less affected by harmonics, it is possible to determine that the earth voltage is caused by the leakage of AC commercial power by calculating the effective value, the content rate and the number of zero crossings based on the measured earth voltage. Accuracy and reliability.

The earth leakage detection device 1000 generates the earth voltage by the leakage of the AC commercial power supply based on at least one of the effective value of the earth voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, the number of zero crossings, and the number of distortions. Based on the determined result, the area where the earth voltage is measured may be determined as a suspected short circuit area.

The earth leakage detecting apparatus 1000 determines whether the effective value of the ground voltage exceeds a preset threshold voltage value (S1109).

The earth leakage detecting apparatus 1000 determines whether the voltage content exceeds the preset voltage content when the effective value of the ground voltage exceeds a preset threshold voltage value (S1110).

When the voltage content rate exceeds the preset voltage content rate, the earth leakage detecting apparatus 1000 determines whether the total harmonic distortion rate is less than the preset total harmonic distortion rate (S1111).

When the total harmonic distortion rate is less than the preset total harmonic distortion rate, the earth leakage detecting apparatus 1000 determines whether the distortion rate for each harmonic component is less than the preset distortion rate for each harmonic component (S1112).

The earth leakage detecting apparatus 1000 determines whether the number of zero crossings corresponds to a preset number of times when the distortion rate of each harmonic component is less than the preset distortion rate of each harmonic component (S1113).

When the number of zero crossings coincides with a preset number of times, the earth leakage detecting apparatus 1000 determines whether the number of distortions is less than the preset number of times (S1114).

When the number of distortions is less than the preset number of times, the ground fault detecting apparatus 1000 determines that the ground voltage is caused by a short circuit of the AC commercial power supply (S1115).

The above-described method of determining the suspected short circuit area is merely an example. The present disclosure is not limited thereto.

36 is a flowchart illustrating a method of determining a ground fault point according to another exemplary embodiment of the present invention.

If it is determined that the ground voltage measured at the power line PEN is caused by the leakage of the AC commercial power supply, the ground fault detecting apparatus 1000 follows the path of the power line embedded in the power line PEN ground measuring the ground voltage, and the actual ground fault is The point of occurrence can be judged as a short circuit point.

First, the ground fault detecting apparatus 1000 may receive a magnetic field signal generated from the sensing current generating device (S1201).

As described above, the detection current generating device injects a current signal to the power line and the center line in the suspected short circuit area, the earth leakage detection device 1000 receives a magnetic field signal generated by the detection current flowing through the power line and the center line. can do.

The earth leakage detecting apparatus 1000 may search for the path of the power line embedded in the suspected earth leakage region based on the received magnetic field signal (S1202).

For example, the ground fault detecting apparatus 1000 may determine a point where the magnetic field signal magnitude is the maximum point as an embedded power line path. In addition, the ground fault detecting apparatus 1000 may search for the direction of the path in which the power line is embedded based on the magnetic field signal polarity.

The electrical leak detecting apparatus 1000 may receive an electrical leak detecting voltage signal generated from the electrical leak detecting voltage signal generator (S1203).

As described above, the earth leakage detection voltage signal generator transmits the earth leakage detection voltage signal, which is a DC pulse voltage, to the power line. When the power line is shorted, the ground fault detection voltage signal is included in the AC commercial power supply to measure the ground voltage. Since the ground voltage measured by the ground fault detection apparatus 1000 also includes harmonic components, it is difficult to determine whether the pulse voltage component is a ground fault detection voltage signal or a harmonic component in the ground voltage. Therefore, the earth leakage detection voltage signal generator transmits the earth leakage detection voltage signal after a predetermined time from the time at which the detection current generator transmits the detection current. The ground fault detecting apparatus 1000 may detect a pulse voltage component as a ground fault detection voltage signal from a ground voltage measured after a predetermined time, based on a time when the magnetic field signal generated by the received sensing current is received.

The earth leakage detecting apparatus 1000 may set a logic value according to whether the earth leakage detection voltage signal is received (S1204).

The electrical leak detecting apparatus 1000 may determine whether the set logic value coincides with a logic value of the electrical leak detecting voltage signal generated by the electrical leak detecting voltage signal generator (S1205).

When the ground fault detection apparatus 1000 is identical to the set logic value and the logic value of the ground fault detection voltage signal, the ground fault detection apparatus 1000 may determine a point at which the magnitude of the ground fault detection voltage signal has the maximum value as the ground fault point (S1206).

If the earth leakage detection voltage signal has a maximum value, the earth leakage detecting apparatus 1000 may determine a point at which the earth leakage detection voltage signal is received as the earth leakage point (S1207).

Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, instructions, information, signals, bits, symbols, and chips that may be referenced in the above description may include voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields. Or particles, or any combination thereof.

One of ordinary skill in the art of the disclosure will appreciate that the various illustrative logical blocks, modules, processors, means, circuits and algorithm steps described in connection with the embodiments disclosed herein may be implemented in electronic hardware, It will be appreciated that for purposes of the present invention, various forms of program or design code, or combinations thereof, may be implemented. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. One skilled in the art of the present disclosure may implement the described functionality in various ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various embodiments presented herein may be embodied in a method, apparatus, or article of manufacture using standard programming and / or engineering techniques. The term "article of manufacture" includes a computer program, carrier, or media accessible from any computer-readable device. For example, computer-readable media may include magnetic storage devices (eg, hard disks, floppy disks, magnetic strips, etc.), optical discs (eg, CDs, DVDs, etc.), smart cards, and flash memory. Devices, such as, but not limited to, EEPROM, cards, sticks, key drives, and the like. In addition, various storage media presented herein include one or more devices and / or other machine-readable media for storing information. The term “machine-readable medium” includes, but is not limited to, wireless channels and various other media capable of storing, retaining, and / or delivering instruction (s) and / or data.

It is to be understood that the specific order or hierarchy of steps in the processes presented is an example of exemplary approaches. Based upon design priorities, it is understood that the specific order or hierarchy of steps in the processes may be rearranged within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, but are not meant to be limited to the specific order or hierarchy presented.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure should not be limited to the embodiments presented herein but should be construed in the broadest scope consistent with the principles and novel features presented herein.

Claims (11)

A ground voltage measuring unit measuring ground voltage;
An ADC unit for sampling the measured ground voltage and converting the measured ground voltage into a digital value;
An effective value calculator configured to calculate an effective value of the ground voltage converted into the digital value;
A Fourier transform unit for performing a Fourier transform on the measured ground voltage based on the effective value of the converted ground voltage to calculate a harmonic component-specific voltage that is an integer multiple of a fundamental frequency—the power frequency of an AC commercial power source;
A content rate calculator for calculating a voltage content ratio of the fundamental frequency to a voltage obtained by summing the voltages of the harmonic components based on the voltage for each harmonic component;
A harmonic distortion calculator for calculating a total harmonic distortion and a harmonic distortion factor based on the voltages of the harmonic components;
A zero crossing calculation unit for calculating the number of zero crossings in which the ground voltage converted into the digital value passes through a zero voltage during a preset time T1; And
The ground voltage is generated by the leakage of the AC commercial power based on at least one of an effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, and the number of zero crossings. A ground fault suspect zone determining unit configured to determine a ground fault suspect area based on the result of the determination and determining the ground voltage;
Including,
Earth leakage detection device.
The method of claim 1,
The preset time T1 is
A time that is a preset integer multiple of the period of the AC commercial power source,
Earth leakage detection device.
The method of claim 1,
A distortion calculation unit for calculating the number of distortions for which the polarity of the change amount of the ground voltage is changed based on the ground voltage converted into the digital value for each sample included in the preset time T1 from the ADC unit;
More, and
The short circuit suspected area determination unit,
Determining a suspected short circuit area based on at least one of an effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, the number of zero crossings, and the number of distortions;
Earth leakage detection device.
The method of claim 3, wherein
The distortion calculation unit,
After the digital value of the first ground voltage sampled and converted and the next sampling period, the polarity of the first change amount of the digital value of the second ground voltage sampled and converted and after the digital value of the second ground voltage and the next sampling period Calculating the number of distortions by determining that distortion occurs due to harmonics when the polarity of the second change amount of the digital value of the third earth voltage sampled and converted is different;
Earth leakage detection device.
The method of claim 1,
The ground voltage measuring unit,
An electrode connected to measurement point a, which is an arbitrary point on the ground surface;
An electrode connected to a measuring point b which is an arbitrary point on the earth's surface different from the measuring point a;
An array of resistors connected in parallel with the measuring point a and the measuring point b; And
A voltage measuring unit measuring a voltage between both ends of the resistor array;
Leakage detection device comprising a.
The method of claim 1,
The zero crossing mountain unit,
During the preset time T1, when the polarity of the ground voltage changes, the number of zero crossings passing through the zero voltage is calculated.
Earth leakage detection device.

The method of claim 1,
The short circuit suspected area determination unit,
The effective value of the converted ground voltage exceeds a preset threshold voltage value, the voltage content exceeds a preset voltage content, the total harmonic distortion is less than a preset total harmonic distortion, and the distortion rate for each harmonic component is preset. Determining that the ground voltage is caused by the leakage of the AC commercial power, when the distortion rate for each harmonic component is less than the set harmonic component and the number of zero crossings coincides with a preset number of times,
Earth leakage detection device.
The method of claim 3, wherein
The short circuit suspected area determination unit,
The effective value of the converted ground voltage exceeds a preset threshold voltage value, the voltage content exceeds a preset voltage content, the total harmonic distortion is less than a preset total harmonic distortion, and the distortion rate for each harmonic component is preset. Determining that the ground voltage is caused by a short circuit of the AC commercial power when the distortion rate for each harmonic component is less than the set harmonic component, the number of zero crossings corresponds to a preset number, and the number of distortions is less than a preset number.
Earth leakage detection device.
The method of claim 1,
A magnetic field signal receiving unit including a magnetic field sensor to receive a magnetic field signal generated from an exploration current generating device for an earth leakage point exploration;
A ground fault detection voltage signal receiver for determining a pulse voltage component received after a predetermined time from the magnetic field signal as a ground fault detection voltage signal generated from a ground fault detection voltage signal generator;
A power line embedding path searching unit that determines a path of a power line embedded in the suspected short circuit region based on a point where the magnitude of the magnetic field signal is the maximum point; And
An electrical leak point determining unit configured to determine an electrical leak point of the embedded power line based on a magnitude of the electrical leak detection voltage signal;
Further comprising,
Earth leakage detection device.
The method of claim 9,
The earth leakage point determination unit,
A logic value is set according to whether the ground fault detection voltage signal is received. The logic value corresponds to a logic value of the ground fault detection voltage signal generated by the ground fault detection voltage signal generator. Judging the point with the maximum value as the earth leakage point,
Earth leakage detection device.

In the short circuit detection method,
Measuring a ground voltage;
Sampling the measured ground voltage and converting the measured ground voltage into a digital value;
Calculating an effective value of the ground voltage converted into the digital value;
Calculating a voltage for each harmonic component that is an integer multiple of a fundamental frequency—a power frequency of an AC commercial power source—by Fourier transforming the measured ground voltage based on the effective value of the converted ground voltage;
Calculating a voltage content ratio of a fundamental frequency to a voltage obtained by summing the voltages of the harmonic components based on the voltages of the harmonic components;
Calculating a total harmonic distortion and a harmonic distortion factor based on the voltage for each harmonic component;
Calculating a number of zero crossings during which a ground voltage converted to the digital value passes a zero voltage for a preset time T1; And
The ground voltage is generated by the leakage of the AC commercial power based on at least one of an effective value of the converted ground voltage, the voltage content rate, the total harmonic distortion rate, the distortion rate for each harmonic component, and the number of zero crossings. Determining that the area of the ground voltage is measured as a suspected short circuit based on the determined result;
Earth leakage detection method comprising a.

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